*{
    margin: 0;
    padding: 0;
}

#div1{
    width: 200px;
    height: 200px;
    background-color: aqua;

    position: absolute;

    z-index: 2;
}

#div2{
    width: 200px;
    height: 200px;
    background-color: rgb(255, 0, 0);
    
    position: absolute;
    top: 100px;
    z-index: 1;
}